Apparatus for separating wax from mineral-oil lubricating stock



July 7, 1925 1,544,747

c. H. 'HAPGOOD APPARATUS FOR SEPARATING WAX FROM MINERAL OIL LUBRICATING STOCK Original Filed Oct. 22, 1921 2 Sheets-Sheet 1 BLENDEDSTOCEK -PREL|MINARY OHILLER I WAXJREE OIL i I [I F q G F H) IL 4INTERMEDIATE emu. 5 Li Q Q FINAL CHILLER I & CHILLED STOCK AIME/Y5K July7, 192 5. 1,544,747 C.H.HAPGOOD APPARATUS FOR SEPARATING WAX FROMMINERAL OIL LUBRICATING S TOCK ri inal Filed Obt. 22. 1921 I 2Sheets-Sheet 2 WAX DISTILLATE.

STEAM -4 i at Nutley, county of Essex,

Patented July 7, 192 5 UNITED STA Tsar-Artur orl-"lcs.

cums HOWARD nareoon'onuu rnny, NEW mnsn, assienon TO THE DE fawn.

SEPABATOR COMPANY, OF NEW YORK,

11. xi, A co'nrone'uon on NEW JERSEY,

APPARATUS FOR, SEPARATING- WAX rnom' npmnAL-on. LuBBIcA'rmG- smoox.

' Original application filed O ctober a,

To all whom it may concern: Be it known that I, CYRUS HOWARD HAP-cooD,-a'c itizen of the UniteoLStates, residing and State of New Jersey,have invented a new and useful Improvement in Apparatus for SeparatingWax from Mineral-.Oil Lubricating Stock, of which the following isa'full, clear, and exact description, reference being had to theaccompanying drawings, which form a. part of this specification. A

In the refining of paraflin base crude oil,

it is customary to distill 01f successively.

products of successively higher boiling points, such as naphtha,illuminating oil, gas oil and wax distillates, leaving as a resi duewhat is commonly known as cylinder trifugal bowl.

stock or bright stock. This bright stock carries in solution asubstantial proportion of amorphous wax (petrolatum) which it isnecessary or desirable to separate from the oil. The wax distillatescarry in solution a substantial proportion of crystalline wax (paraflin)which it is necessary or-desirable to separate from the oil.

It is known to eifect the separation of wax from bright stock bydiluting the stock -with naphtha, bringing the blended stock in heatexchange relation with refrigerated brine for the purpose of throwingthe wax out of solution, then separating the wax from the oil byfiltration or settlement, and distilling oif the naphtha.

It is also known to eilect the separation of wax from wax distillates bysimilarly cooling with refrigerated brine followed by filtration orsettlement.

The settlement and filtration processes are bulk processes, involvingthe use of large plants occupying much room, the handling of a largeamount of stock at one time and the expenditure of considerable time. An

I expensive part of the plant is that required batch, to substitute asmall, eflicient and economical plant for a large, ineflicient andwasteful plant, and particularly 'to simplify and cheapen therefrigerating "treatment. In efi'ecting this result I avail myself ofknown expedients,- such as heat (or cold) exchange, chilling by directabsorption of heat by ammonia, andcentrifu ation, all combined to-form aprocess whic is unitarily new.

.I am aware that it has been proposed to separate wax from cylinderstock continuously by refrigerating the stock and sep aratmg the oil andthe precipitated Waxes by means of centrifugal force, using brine as anagent to carry the wax out of the cen- This process'is efl'ective toseparate the oil fromthe wax, but the resultant mixture of brine and waxis diflicult of separation. My process does not necessarily involve, butpreferably excludes, the use of cold brine to carry the wax out of thecen trifugal bowlr In any case, neither of the centrifugal processesherein described is herein claimed per se, but only as a step incombination with the preceding refrigerating treatments and other.associated steps.

My treatment of bright stock and my treatment -of wax distillates havecertain features in'common and these features, when associated as hereindescribed, comprise my invention in its broader aspect. In view,however, of the differences between the two treatments, I shall describeeach separately.

Referring now to the accompanyingdrawings, in Wlllch I have illustrateda preferred embodiment of my invention Fig. 1 is a diagram of anapparatus ar-. ranged to carry out myprocess as adapted to the searation of amorphous wax (petrolatum) rom bright stock.

Fig. 2 is a diagram of an apparatus arran ed to carry out my process asadapted to t e separation of crystalline Wax (paraf fin) from waxdistillates.

Referring fir t to Fig. 1: a is a tank containin bright stock with waxin solution and diluted with naphtha. This tank is connected with adouble pipe preliminary chiller comprising a pipe 6 adapted to conveythe blended stock toward the final chiller or chillers, and a pipe 0 (inheat exchange relation with pipe 1)) adapted to con- 1921,'Serja.l' No.509,669. Divided. and this application filed October 11, mag. SerialNo.598,674.:

vey the separated cold waxfree oil toward a still for driving off thenaphtha. The blended stock and the wax-free 011 flow in oppositedirections so that the stock gradually loses heat while the oil isgradually heated to normal temperature. I It may be assumed, forpurposes of illustration, that the temperature of the stock is reducedin this chiller from (say) 90 F. to 45 F.

The preliminary chilled blended stock.- then flows through anintermediate double 7 I pipe chiller comprising a pipe 03 adapted toconvey the stock to the final chiller and a pipee (in heat exchangerelation with pipe (Z) adapted to circulate ammonia which has beencompressed, condensed and expanded in the manner well known in the artand known as the direct expansion system of refrigeration. The currentof expanded, gaseous, low-temperature ammonia flows in a directionopposite to that of the stock and gradually reduces. the temperaturethereof until, when the blended stock emerges from the pipe 03', it hasbeen substantially reduced in temperature, say to about 20F.

The thus chilled blended stock then flows through a final double pipechiller comprising a pipe d adapted to convey the stock to a centrifugalseparator and a pipe e (in heat exchange relation with pipe 03') adaptedto circulate ammonia which has been compressed, condensed and expanded.The current of ammonia flows in a direction opposite to that of thestockand gradually reduces the temperature thereof until when the blendedstock emerges from the final pipe 0 of the doublepipe chiller, to astill in which the naptha is driven off.

In the ammonia circulating system, 2' is the condenser, wherein thecompressed ammonia at a high pressure is reduced in temperature. j isthe ammonia reservoir. The ammonia pipes e and e. ofithe last twochillers are arranged in parallel. The two pipes have independentexpansion valves and 7c, the ammonia, as it escapes through eithervalve, being greatly reduced in pres sure and expanding from a liquid ofrelatively high temperature 'to a gas of very low temperature, as wellknown in the art. From the pipes e and e the ammonia gas, which hasabsorbed heat from the stock,

flows to the respective compressors z, 2,

process is continuous and that a large vol-.

ume of stock may be treated in a comparatively short time; and that theutmost economy in cost of operation is achieved. With respect to thelast named advantage, it is clear that thelowering of the temperature ofthe incoming blended stock by'heat absorption by the outgoingcentrifugally separated oil is effected by means of a liquid that hasbeen already necessarily refrigerated; that the expense of refrigerationis only that required to reduce the tem erature of the stock through acomparative y small temperature range; and that thellater chilling iseffected by direct expansion of ammonia and not by means of anammoniarefri erated intermediate liquid.

Re erring to Fig. 2, which-is an apparatus for the treatment of waxdistillates; m is a tank containing awax distillate. This distillateneed not be, and preferably is not, diluted with naphtha. The tank m iscon- .nected with a double pipe preliminary chiller comprising a pipe1:. adapted to carry the distillate toward the final chiller, and a pipe0 (in heat exchange relation with pipe run it through which theseparated cold wax-,

free oil travels on its way to storage.

The preliminary chilled stock then flows through one,or more double pipechillers 1', r forming part of a direct expansion ammonia refrigeratingsystem the same as that diagrammed inFig. 1. The distillate emerges fromthe final cooler reduced ,to a temperature of from 20 F. to 35 F.,preferably about 25 F. At this temperature the crystalline waxes havebeen thrown out of solution.

It is more difiicult to centrifugally separate from oil and dischargefrom the bowl crystalline wax than it is to separate and dischargeamorphous wax. If no heavy liquid agent is added to sludge the wax outof the bowl, no wax at all will be discharged from the bowl unless, inthe first instance, the distillate has been diluted with naphtha. Eventhe use of a sludging liquid, such as refrigerated brine, will notprevent the wax from building up rapidly within the bowl, and moreoverthe mixture of brine and wax is very difficult of separation. In thepres ent process, I admit water, at a temperature of about 180 F., froma reservoir t, into the peripheral part of the separator bowl u,heat-insulating the water feed channel Within the bowl from thedistillate feed,

channel and from the separating compartment. 1 The hot water flowingalong the periphery of the .bowl melts the layer ofwax immediatelyadjacent thereto, and such wax, being in a liquid condition, readilyflows out of the bowl. This part of the process is not herein claimedper se, as it is the joint invention of Selden H. Hall and myself andsweating pans or may be freed from any water whichthey carry oil" bytreatment in a second centrifugal separator y. v

The water in tank 25 is kept atthe de: sired temperature by means ofsteam coils w. The pipes in the coolers through which the distillateflows to the centrifuge are pre vented from clogging with wax by meansof internal agitators on shafts to which are secured driven sprockets00.

It will be evident that the just described process for treating waxdistillates and the previously described process for treating brightstock have features both of identity and similarity, and that to theextent that the processes are alike, the advantages are the same.

While that step of the refrigerating treatment comprising the cooling ofthe stock by direct expansion of ammonia may be carried out in a singlechiller instead of in a plurality of chillers, as illustrated and de- 1scribed, I have found that the power required (measured in terms of H.P. hours to make one ton of refrigeration) will diminish with the numberof chillers employed. The use of at least a plurality of chillers istherefore not a mere matter of convenience, or a mere duplication, buteffects a substantial saving in cost of refrigeration.

' I have not herein claimed the process disclosed, as the same forms thesubject-matter of an application filed by me October 22,

1921, Serial No. 509,669 matured into Patent No. 1,464,707 ofwhich thisapplication is a division.

Having now fully described my invention, what I claim and desire toprotect by Letters Patent is:

1. An apparatus for treating lubricating oils containing waxes insolution to continuously separate the wax from the oil, comprising apreliminary double pipe chiller and a final double pipe chiller, saidchillers 1 comprising a continuous conduit through which the solution ofoil and wax is adapted to continuously flow, each of said chillerscomprlsing also a second conduit arranged in heat exchange relation withthefirst conduit and through which the chilling fluid 1s passed, and acentrifuge communicating with said first conduit and into which therefrigerated stock is adapted to continuously feed, said centrifugehaving a discharge for wax-free oil communicating with the secondconduit of the preliminary chiller.

2; An apparatus for treating lubricating oils containing waxes insolution to continuously separate the wax from the oil, comprising apreliminary chiller and a multistage chiller, said chillers comprising acontinuous conduit through which the solution of oil and wax is adaptedto. continuously flow, each of said chillers comprising also a secondconduit arranged in heat exchange relation with the first conduit andthrough -which the chilling fluid is passed, the said second conduits ofthe different stagesiof the multi-stage chiller being arranged in parallel, a centrifuge communicating with said first conduit and into whichthe refriger-- ated stock is adapted to continuously feed,saidcentrifuge having a discharge for waxfree oilcommunicating'with thesecond con duit of the preliminary chiller, and means to circulate arefrigerating fluid through the said second conduits of the multi-stagechiller.

An apparatus for treating lubricating oils containing waxes in solutionto continuously separate the wax from the oil, comprising a preliminarydouble pipe chiller, an intermediate double pipe chiller and a finaldouble pipe chiller, said chillers comprising a continuous conduitthrough which the solution of oil and wax is adapted to continuouslyflow, each of said chillers comprising also a second conduit arranged inheat exchange relation with the first conduit and-through which thechilling fluid is passed, the second conduits of said intermediate andfinal chiller being arranged in parallel, a centrifuge communicatingwith said first conduit and into which the refrigerated stock is adaptedto continuously feed,

and condense the ammonia leaving the intermediate and final chillers.

4. An apparatus for treating lubricating oil stock containing Waxes insolution to continuously separate the wax from the oil, comprising acontinuous conduit through which the stock is adapted to continuouslyflow, a centrifuge communicating with said conduit and into which thechilled stock is adapted to continuously feed, said centrifuge having adischarge for oil-free wax and a discharge for chilled wax-free oil, asecond conduit communicating with the second of said discharges and inheat exchange relation with the fore part of said first conduit, a thirdconduit in heat exchange relation with that part of the first conduitbetween the second conduit and the centrifuge, and means independent ofsaid centrifuge discharges to supply refrigerating fluid to the thlrdconduit.

p In testimony of which invention, I have hereunto set my hand, at NewYork, on this 12th day of September, 1922.

oYRUs HOWARD HAPGOOD.

